NASA Counts 4,700 Potentially Hazardous Near-Earth Asteroids

coondoggie writes "NASA continues to get a better handle on the asteroids buzzing around in space saying today that there are roughly 4,700 potentially hazardous asteroids, or as NASA calls them PHAs. NASA says these PHAs are a subset of a larger group of near-Earth asteroids but have the closest orbits to Earth's – passing within five million miles (or about eight million kilometers) and are big enough to survive passing through Earth's atmosphere and cause damage on a regional, or greater, scale."